(a) Field of the Invention
This invention relates to permanent suspension dosage forms of water sensitive drugs particularly suitable for oral administration without reconstitution. These dosage forms have exhibited unique long term stabilites and extended shelf lives. They possess excellent taste characteristics, and bioavailabilities.
(B) Prior Art
Commercial aqueous suspension of antibiotics for oral administration have limited shelf lives because of the instability of the antibiotic in aqueous media. For example, commercial ampicillin oral suspensions, after reconstitution with water according to manufacter's instructions will decompose about 0.2% per day at 4.degree. C. and 0.6% per day at 25.degree. C. Therefore, these dosage forms must be marketed dry, as a powder, for reconstitution with water immediately prior to dispensing to the patient.
U.S. Pat. No. 3,097,135 describes a prior art approach to overcoming this instability problem by providing a method for the stabilization of erythromycin in an anhydrous emulsion for oral administration. A variety of emulsifying agents and processing temperatures of 85.degree.-90.degree. C are described.
West German Offenlegungsschrift No. 2,250,680 describes the preparation of stable suspensions suitable for antibiotics which employ a variety of "necessary agents," including an emulsifying agent, "in the proper ratio" to achieve a suspension alleged to be stable, although without any supporting data.
Oral pharmaceutical compositions employing mono-, di- or triglycerides of saturated acids having 6 to 12 carbon atoms as "adsorption promoting agents" for a variety of drugs are described in Belgian Pat. No. 807,312. The thrust of this patent is to facilitate the gastro-intestinal adsorption of the drug, thus, intensifying or promoting its therapeutic effect. No stability data or shelf-life characteristics of the resulting compositions are given.
It is an object of this invention to provide permanent suspensions of drugs dispersed in an anhydrous vehicle constituting a unique structurized suspension. The compositions of this invention do not require heat during manufacture, nor do they require emulsifying agents to achieve commercially acceptable stability and exceptional shelf-life.